The approaches described in this section could be pursued, but are not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Internet Protocol (IP) telephony is a technology that is being widely implemented and gaining widespread acceptance. However, requirements for deployment of IP telephony systems in many countries include the ability to locate emergency callers and to forward emergency calls to appropriate public safety agencies. Hence, emergency response systems' ability to track user and phone location changes add to the power of IP telephony systems.
Emergency Response Service
Emergency systems are critical in any environment, as such systems are a matter of life and death. Countries like the United States have created a 911 concept through which a user can ask for help during an emergency. The 911 center that receives the call must be able to determine the location of the user and dispatch help from the closest location possible. In the case of IP telephony, the user can move his phone from one location to another and seamlessly use all the offered IP telephony services. Thus, when a user moves from one location to another, the location must be tracked and provided to emergency personnel. This makes IP-based 911 systems complex.
In a series of orders since 1996, the Federal Communications Commission (FCC) has taken action to improve the quality and reliability of 911 emergency services for wireless phone users. E911 (sometimes referred to as E.911) refers to “enhanced 911” for wireless services. An important feature of E911 services is to provide emergency services personnel with location information that will enable them to locate and provide assistance to wireless 911 callers much more quickly.
Such a feature is equally important and relevant to IP telephony environments. For example, assume a hypothetical scenario in which a telecommuter has an IP phone that is registered with a call manager in City A but who is physically located in City B. In such a scenario, emergency personnel in City B would need to be notified of an incoming 911 or emergency call because that is where the emergency exists, rather than at the location of the call manager, i.e., City A. Hence, VoIP emergency response (“ER”) services or applications provide an E911 facility for users in IP telephony environments. Furthermore, efficient 911 response is not always ensured on large PBX systems at corporations, universities and other organizations with extensive private phone switchboards. Unlike a residential phone, business phones are often not linked directly with the nation's dispatch system for fire, police and medical help and the location of such a phone is not registered in the 911 system's automatic location information (ALI) database, which helps dispatchers capture the exact location of an emergency caller.
ER applications typically perform the following, in the context of the group of users to which an application is serving: (1) accept or intercept calls initiated to 911; (2) determine the location of the caller; (3) determine the local line that actually needs to be called for the emergency, e.g., the PSAP (Public Safety Answering Point) associated with the location from which the caller made the 911 call; (4) route the call to the local line; and (5) maintain the ID and location of the caller so that the PSAP can call back if necessary. In addition, some ER applications also route the call to an associated OSAN (On-Site Alert Number). A PSAP refers to a physical location where 911 calls are received and then routed to the proper emergency services. An OSAN refers to a location within an organization where a notification is sent when a 911 call is made by a user within the organization.
One commercially available emergency response application or service is Cisco Emergency Responder (CER) available from Cisco Systems, Inc., which can quickly determine which Ethernet switch port is connected to a roaming caller's IP phone. In general, CER matches the MAC addresses of Ethernet switch ports currently connected to IP phones with the MAC addresses and associated phone extensions of the IP phones registered in a device acting as a VoIP call manager. More specifically, when CER is initially configured, a network manager defines emergency response location (ERL) entities for individual Ethernet switch ports across the network. ERL information includes the switch port number, street address, building name, floor number, room number, emergency contact personnel, and other information relevant to that port. From there, an emergency location identification number (ELIN) is associated with each ERL. The CER uploads the ELINs to the local service provider's ALI database. At the time of an emergency call, the caller's IP phone number, listed in the call manager database, is translated by the CER into the ELIN of the port to which it is connected.
The foregoing discussion illustrates that ER applications provide extremely important lifeline services. However, ER applications typically are the least-exercised component of a VoIP service and, therefore, are susceptible to unnoticed failures. For example, 911 systems are rarely used in a “production” situation, which is during an actual emergency, so it is possible that the system may not be functioning, unbeknownst by the administrator of the system. This leads to situations where one cannot summon help when required. Furthermore, it is often illegal for a network administrator or management system to make “dummy” 911 calls to check the system.
Based on the foregoing, there is a clear need for a technique for proactively and non-intrusively monitoring the performance and functionality of an emergency response service in an IP telephony environment.